AddLayer takes 3 arguments:
AddLayer (data_frame, add_layer, {add_position})
where data_frame must be instance of arcpy.mapping.DataFrame, add_layer must be instance of arcpy.Layer.All you have to do is define data frame of mxd and create arcpy.Layer()'s from paths so:
TemplateLayers=(r"\\...\TemplateLayers.txt")
lyrDict={}
with open (TemplateLayers) as f:
for line in f:
key,val=line.split(",")
lyrDict[key]=val
f.close()
print lyrDict
mxd = arcpy.mapping.MapDocument('path\\to\\mxd.mxd')
df = arcpy.mapping.ListDataFrames(mxd)[0]
#Step 2: Pull the layers into the MXD at the bottom of the data frame from the dictionary.
for val in lyrDict.values():
arcpy.mapping.AddLayer(df,arcpy.Layer(val),"Bottom")
That should do.RegardsArek